Multi-component extruder method

Abstract

A multi-component extruder for producing a multi-component profiled member has at least two individual extruders for extruding a single-component profiled member. Each individual extruder has a housing with a chamber for receiving the extrudable material and an extruder shaft rotatably supported in the chamber. Each individual extruders has an extruder mold nozzle for continuously extruding the single-component profiled member. The individual extruders are equipped with devices for measuring pressure and temperature. A common extruder head has a confluence zone in which the extruder nozzles are arranged to combine the single component profiled members to the multi-component profiled member. A device for measuring the multi-component profiled member is provided. A control device is provided for individually controlling the number of revolutions of each individual extruder according to a preset nominal value based on the nominal characteristic value of the multi-component profiled member, on the extrudable materials, and on the extrusion mold nozzles. The control unit serves to control the actual number of revolutions upon detecting deviations of the measured characteristic value of the multi-component profiled member from a nominal characteristic value as a function of detected deviations of the measured values for temperature and pressure within the individual extruders from nominal pressure values and temperature values.

What we claim is: 
     
       1. A method for controlling the composition of a multi-component profiled member, said method comprising the steps of: extruding at least two single-component profiled members in respective individual extruders;   combining the single-component profiled members to a multi-component profiled member in a common extruder head;   measuring actual temperature values and actual pressure values within each one of said individual extruders;   comparing the actual temperature values and the actual pressure values of each one of said individual extruders to nominal temperature values and nominal pressure values of each one of said individual extruders;   measuring the width of the single-component profiled members of the multi-component profiled member for determining deviations of the measured width from a nominal width;   adjusting that one of said individual extruders where the actual temperature values and actual pressure values deviate from the nominal temperature values and nominal pressure values; and   controlling a mass flow of that one of said individual extruder, for which deviations of the measured width from the nominal width have been detected by changing the number of revolutions or the velocity of the individual extruder until the nominal width of the single-component profiled member is reached.   
     
     
       2. A method according to claim 1, wherein in the step of adjusting that one of said individual extruders is adjusted where an average pressure value of the actual pressure values measured at at least two pressure measuring locations and the actual temperature value measured at at least one temperature measuring location deviate from an average nominal pressure value and from the nominal temperature value. 
     
     
       3. A method according to claim 1, wherein in the step of adjusting the number of revolutions of the individual extruder is adjusted. 
     
     
       4. A method according to claim 3, further including the step of saving actual values of the number of revolutions of the individual extruders for multi-component batch processes in conjunction with identification information for the multi-component extruder, for the extruded material, and the resulting multi-component profiled member, and further including the step of programming the multi-component extruder with the saved actual values of the number of revolutions as nominal values for a new multi-component batch process having the same composition of components, the same distribution of components within the individual extruders, and a substantially identical multi-component profiled member. 
     
     
       5. A method according to claim 3, wherein at the beginning of a multi-component batch process the multi-component profiled member is measured and the measured characteristic values are compared to nominal characteristic values of the multi-component profiled member, wherein, upon coinciding of the nominal characteristic values and the actual characteristic values, at a plurality of predetermined locations the actual temperature values and the actual pressure values within at least one individual extruder are detected, wherein the actual pressure values are averaged, and wherein the actual temperature values and the actual averaged pressure values are compared to the nominal temperature values for pressure and temperature for the extruded material, known for the selected value of the number of revolutions of the individual extruder and for the selected characteristic value of the multi-component profiled member, in order to check the identity of the material present within the extruder with the desired material to be processed. 
     
     
       6. A method according to claim 5, wherein a correlation of the actual averaged pressure values and the actual temperature values, when the actual mass flow is identical to the nominal mass flow, to known material-typical averaged pressure values and actual temperature values, determined for known materials within the extruder in connection with a certain mold nozzle, is carried out for determining the material present in the extruder.